Surrounding environment recognition device

ABSTRACT

A surrounding environment recognition device includes an image capturing unit that captures a peripheral image, and a traffic signal detecting unit, which sets a search region with respect to the peripheral image, and detects a traffic signal inside of the search region. The search region becomes smaller as the distance from the image capturing unit is farther away.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a surrounding environment recognitiondevice for detecting traffic signal lights using a peripheral image.

Description of the Related Art

Japanese Laid-Open Patent Publication No. 2012-168592 (hereinafterreferred to as “JP 2012-168592A”) discloses the detection of red lightsignals Lr and arrow signals A of traffic lights S, based on images Tthat are captured by an image capturing means 2 (abstract). According toJP 2012-168592A, it is disclosed that, upon detection of an arrow signalA, the recognition method is switched corresponding to the distance to ared light signal Lr (FIG. 15).

Japanese Laid-Open Patent Publication No. 2007-034693 (hereinafterreferred to as “JP 2007-034693A”) discloses extracting a red colorluminance part from an image captured by a front monitoring camera 4, tothereby detect a red signal light of a traffic signal (abstract andparagraph [0017]). Further, in the case that a red signal light isdetected, a judgment is made as to whether or not the traffic signalexists on the traveling path of the driver's own vehicle (abstract).Whether or not the traffic signal exists on the path of the driver's ownvehicle is judged using map information from a navigation device 11(paragraph (0027)).

SUMMARY OF THE INVENTION

In each of JP 2012-168592A and JP 2007-034693A, detection of trafficsignals is carried out on the basis of searching the entirety of acaptured imaged, and therefore, the processing burden is high, or thelength of the processing cycle required to carry out searchingconcerning a specified region is made longer, which in turn influencesaccuracy in the detection of traffic signals.

The present invention has been devised taking into consideration theaforementioned problems, and has the object of providing a surroundingenvironment recognition device, in which the processing load can belightened, or detection accuracy can be improved.

A surrounding environment recognition device according to the presentinvention includes an image capturing unit that captures a peripheralimage, and a traffic signal detecting unit, which sets a search regionwith respect to the peripheral image, and detects a traffic signalinside of the search region. In particular, the search region becomessmaller as a distance from the image capturing unit is farther away.

According to the present invention, the search region used duringdetection of the traffic signal becomes smaller as the distance from theimage capturing unit is farther away. Therefore, the traffic signal canbe detected with a small processing burden or computational loadcorresponding to the distance from the image capturing unit.Alternatively, by shortening the processing cycle required to carry outsearching of the specified region, the detection accuracy at whichtraffic signals are detected can be improved.

The traffic signal detecting unit may set a search window for searchinginside of the search region, and may scan the search window within thesearch region to thereby detect the traffic signal. In this case, thesearch window may become smaller as the distance from the imagecapturing unit is farther away. According to this feature, the trafficsignal can be detected accurately by the search window corresponding tothe distance from the image capturing unit.

The surrounding environment recognition device may further include aroad line recognition device that recognizes a road line, and thetraffic signal detecting unit may change a position of the search regioncorresponding to a position of the road line. According to this feature,by removing from the search region a range in which the traffic signalcannot exist due to the relation thereof with the road line, thecomputational load can be lightened, or accuracy can be enhancedaccompanying shortening of the search cycle.

The road line recognition device may acquire distance information to thetraffic signal from an external device or from a storage deviceincorporated in the vehicle, and may set the search region based on thedistance information to the traffic signal. According to this feature,by specifying the distance to the traffic signal using the distanceinformation, and setting the search region based on the distance, theaccuracy in detecting the traffic signal can be enhanced, or a reductionin computational load can be realized.

The road line recognition device may acquire height information of thetraffic signal from an external device or from a storage deviceincorporated in the vehicle, and may set the search region based on theheight information of the traffic signal. According to this feature, byspecifying the height of the traffic signal using the heightinformation, and setting the search region based on the height, theaccuracy in detecting the traffic signal can be enhanced, or a reductionin computational load can be realized.

The above and other objects, features, and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings in which a preferredembodiment of the present invention is shown by way of illustrativeexample.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a vehicle in which a surroundingenvironment recognition device according to an embodiment of the presentinvention is incorporated;

FIG. 2 is a view showing an example of a peripheral image when a trafficsignal detection control process is carried out according to the presentembodiment; and

FIG. 3 is a flowchart of the traffic signal detection control processaccording to the present embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A. Embodiment

[A1. Description of Overall Configuration]

(A1-1. Overall Configuration)

FIG. 1 is a schematic diagram of a vehicle 10 in which a surroundingenvironment recognition device 14 (hereinafter also referred to as a“recognition device 14”) according to an embodiment of the presentinvention is incorporated. As shown in FIG. 1, in addition to therecognition device 14, the vehicle 10 includes a sensor unit 12 and adriving assistance unit 16. In the vehicle 10, a traffic signal 210 (seeFIG. 2) is detected by the recognition device 14 based on sensorinformation Is (such as image information Ii which will be describedlater) supplied from the sensor unit 12. Information of the detectedtraffic signal 210 is used in the driving assistance unit 16 forassisting driving of the vehicle 10.

(A1-2. Sensor Unit 12)

The sensor unit 12 acquires the sensor information Is that is used inthe recognition device 14 for detecting the traffic signal 210. As shownin FIG. 1, in the sensor unit 12, there are included a camera 20, avehicle velocity sensor 22, a yaw rate sensor 24, and a map informationsupply device 26.

The camera 20 is an image capturing unit that captures a peripheralimage 100 (see FIG. 2) of the vehicle 10, and outputs image informationIi in relation to the peripheral image 100. The camera 20 is fixedthrough a non-illustrated bracket to the front windshield or the roof ofthe vehicle 10. Although in the present embodiment the camera 20 is acolor camera, the camera 20 may be a black and white (monochrome)camera, insofar as the camera is capable of detecting the traffic signal210 (see FIG. 2) based on the peripheral image 100.

The vehicle velocity sensor 22 detects a velocity V [km/h] of thevehicle 10. The yaw rate sensor 24 detects a yaw rate Yr [deg/sec] ofthe vehicle 10.

The map information supply device 26 supplies map information Im asinformation (peripheral information) in relation to the surrounding areaof the vehicle 10. The map information supply device 26 includes acurrent position detector 30 and a map information database 32(hereinafter referred to as a “map DB 32”). The current positiondetector 30 detects the current position Pc of the vehicle 10. The mapDB 32 stores map information Im including the position of the trafficsignal 210. The position in this case can be relatively rough orimprecise, which is sufficient to indicate, for example, whether atraffic signal 210 exists at any given intersection. Alternatively, theposition Ps of the traffic signal 210 may be comparatively detailedincluding a front side and a rear side of the intersection, a height H,and lateral (left/right) information, etc. Furthermore, the imageinformation Im may include the form (vertical, horizontal, etc.) of alight emitting section 214 (see FIG. 2) of the traffic signal 210.

The map information supply device 26 calculates a distance Lsmap [m]from the vehicle 10 (camera 20) to the traffic signal 210 based on thecurrent position Pc and the position Ps of the traffic signal 210, andsupplies the same as distance information Ilmap to the recognitiondevice 14. In this regard, the distance information Ilmap makes up aportion of the map information Im.

The map information supply device 26 can be constituted, for example, asa navigation device. Alternatively, the map information supply device 26may be a device that supplies map information Im to the recognitiondevice 14 without performing route guidance in respect to the driver.

(A1-3. Surrounding Environment Recognition Device 14)

The surrounding environment recognition device 14 detects a trafficsignal 210 that exists in a direction of travel of the vehicle 10. Asshown in FIG. 1, the recognition device 14 includes as constituenthardware thereof an input/output unit 50, a computation unit 52, and astorage unit 54. The recognition device 14 is constituted as anelectronic control unit (ECU) including a central processing unit (CPU)or the like. The input/output unit 50 carries out input and output ofsignals to and from the sensor unit 12 and the driving assistance unit16.

The computation unit 52 serves to control the recognition device 14 as awhole, and operates by executing programs that are stored in the storageunit 54. Such programs may be supplied from the exterior through anon-illustrated wireless transmission device (portable telephone,smartphone, etc.). Further, a portion of such programs can beconstituted by hardware (circuit components).

The computation unit 52 includes a road line detecting unit 60, a searchwindow setting unit 62, a search region setting unit 64, and a trafficsignal detecting unit 66. The road line detecting unit 60 detects roadlines 240 l, 240 r (see FIG. 2) in the direction of travel of thevehicle 10, and outputs road line information 11 in relation to the roadlines 240 l, 240 r. The search window setting unit 62 setsspecifications for search windows 230 a to 230 c (hereinafter referredto collectively as “search windows 230”). The search region setting unit64 sets specifications for search regions 232 a to 232 c (hereinafterreferred to collectively as “search regions 232”). The traffic signaldetecting unit 66 detects a traffic signal 210 and outputs trafficsignal information Isig in relation to the traffic signal 210. Detailsof a control (traffic signal detection control) performed in thecomputation unit 52 will be described later with reference to FIGS. 2and 3.

The storage unit 54 is constituted by a random access memory (RAM) thattemporarily stores data, etc., which is supplied to or from the variouscomputational processes, and a read only memory (ROM), which storesexecutable programs, tables, or maps, etc.

(A1-4. Driving Assistance Unit 16)

The driving assistance unit 16 carries out driving assistance to assistthe driver in driving the vehicle 10 using the calculated results of therecognition device 14. The driving assistance unit 16 includes a brakedevice 70 and a warning device 72. The brake device 70 serves to controla braking force of the vehicle 10, and includes a hydraulic mechanism 80and a brake electronic control unit 82 (hereinafter referred to as a“brake ECU 82”). The brake ECU 82 controls the hydraulic mechanism 80based on the traffic signal information Isig from the recognition device14. In this regard, braking is assumed to be frictional braking which iscarried out using the hydraulic mechanism 80. However, in addition to orin place of frictional braking, a control involving one or both ofengine braking and regenerative braking may be performed.

The warning device 72 informs the driver of an illuminated state of thetraffic signal 210, in particular, a red light signal (i.e., a state inwhich a red lamp 224 of the traffic signal 210 is illuminated). Thewarning device 72 includes a display device 90 and a warning electroniccontrol unit 92 (hereinafter referred to as a “warning ECU 92”). Thewarning ECU 92 controls the display device 90 based on the trafficsignal information Isig from the recognition device 14.

[A2. Various Control]

(A2-1. Outline)

In the vehicle 10 according to the present embodiment, a traffic signal210 is detected using the surrounding environment recognition device 14.In addition, based on information concerning the detected traffic signal210, driving assistance is carried out to assist the driver in drivingthe vehicle 10. Driving assistance includes, for example, in the casethat the vehicle is coming too close to a traffic signal 210 displayinga red light, applying automatic braking and informing the driver thatthe vehicle 10 is approaching the traffic signal 210 with the red light.

Below, the control performed by the surrounding environment recognitiondevice 14 for detecting the traffic signal 210 will be referred to as a“traffic signal detection control”. Further, the control performed bythe driving assistance unit 16 for assisting driving will be referred toas a “driving assistance control”.

(A2-2. Traffic Signal Detection Control)

(A2-2-1. Outline of Traffic Signal Detection Control)

FIG. 2 is a view showing an example of a peripheral image 100 when atraffic signal detection control process is carried out according to thepresent embodiment. FIG. 2 illustrates a case in which the vehicle 10 isbeing driven on a left side of the road. Therefore, a traveling lane 200of the vehicle 10 (driver's own vehicle) is on the left side of theroad, whereas an opposing lane 202 is on the right side of the road. Thetraffic signal 210 of FIG. 2 includes a supporting post 212 and thelight emitting section 214. The light emitting section 214 includes agreen lamp 220, a yellow lamp 222, and the red lamp 224. Further, asshown in FIG. 2, in the traffic signal detection control, the pluralityof search windows 230 a to 230 c, and search regions 232 a to 232 c thatcorrespond to the search windows 230 a to 230 c are used.

The search windows 230 a to 230 c set a range over which the trafficsignal 210 is searched for, and the search windows 230 a to 230 c aremoved (or scanned) within the search regions 232 a to 232 c. The methodfor setting the search windows 230 a to 230 c will be described belowwith reference to step S3 of FIG. 3.

The search regions 232 a to 232 c regulate the range over which thesearch windows 230 a to 230 c are moved, and according to the presentembodiment, are set to sizes that correspond with the distance L [m]from the camera 20. A method for setting the search regions 232 a to 232c will be described below with reference to step S4 of FIG. 3.

(A2-2-2. General Flow of Traffic Signal Detection Control)

FIG. 3 is a flowchart of the traffic signal detection control processaccording to the present embodiment. Each of the process steps of FIG. 3is executed by the computation unit 52 of the surrounding environmentrecognition device 14. In step S1 of FIG. 3, the recognition device 14acquires respective types of sensor information Is from the sensor unit12. The sensor information Is in this case includes the imageinformation Ii from the camera 20, the vehicle velocity V from thevehicle velocity sensor 22, the yaw rate Yr from the yaw rate sensor 24,the current position Pc, and the map information Im from the mapinformation supply device 26.

In step S2, the computation unit 52 (road line detecting unit 60)detects the road lines 240 l, 240 r using the peripheral image 100 fromthe camera 20, and outputs road line information Il in relation to theroad lines 240 l, 240 r. The road lines 240 l, 240 r can be defined bywhite lines or shoulders in the vicinity of the traveling lane 200 andthe opposing lane 202. The road line information Il also includesinformation concerning the trajectory of the road lines 240 l, 240 r.

In step S3, the computation unit 52 (search window setting unit 62) setsspecifications for the search windows 230 a to 230 c using the sensorinformation Is. In step S4, the computation unit 52 (search regionsetting unit 64) sets specifications for the search regions 232 a to 232c using the sensor information Is.

In step S5, the computation unit 52 (traffic signal detecting unit 66)detects the traffic signal 210 while moving the search windows 230 a to230 c within the search regions 232 a to 232 c.

(A2-2-3. Setting of Specifications for Search Windows 230 a to 230 c andSearch Regions 232 a to 232 c (Steps S3, S4 of FIG. 3))

(A2-2-3-1. Initial Settings)

In the initial settings according to the present embodiment, threesearch regions 232 a to 232 c are used. The respective search regions232 a to 232 c are set so that the distance L from the camera 20 becomesfirst through third predetermined values L1 to L3 (e.g., 30 m, 60 m, 90m). Stated otherwise, the search region 232 a is for near distance use,the search region 232 b is for mid-distance use, and the search region232 c is for far distance use. However, the number of search regions 232is not limited to three, and may be two or four or more (for example,any number from four to one hundred). In the present embodiment, forfacilitating understanding, three search regions 232, which is acomparatively small number, are used. Further, one or two search regions232 can be used selectively corresponding to the map information Im,etc.

The camera 20 of the present embodiment is attached to the vehicle 10,and the specifications of the camera 20, e.g., magnification and viewangle, etc., are fixed. For this reason, a relationship is determinedbetween the distance L from the camera 20, and the XY coordinates of the(two dimensional) peripheral image 100, as well as the area thereof inthe XY plane or the like. Therefore, by setting the search regions 232corresponding to the distance L, the traffic signal 210 can be detectedmore accurately.

Thus, according to the present embodiment, the search windows 230 a to230 c and the search regions 232 a to 232 c are set to sizescorresponding with the first through third distances L1 to L3. Morespecifically, the search windows 230 a to 230 c and the search regions232 a to 232 c are made smaller as the distance L from the camera 20becomes farther away. Note that making the search regions 232 a to 232 csmaller implies not only making the lengths of both the X-direction(horizontal direction) and the Y-direction (vertical direction) smaller,but may include a case in which only the length in the Y-direction(vertical direction) is made smaller.

(A2-2-3-2. Correction Using Sensor Information Is)

Next, correction of the specifications of the search windows 230 a. to230 c and the search regions 232 a to 232 c using the sensor informationIs will be described.

(A2-2-3-2-1. Road Line Information Il)

Generally, traffic signals 210 exist laterally or upward of thetraveling lane 200 and/or the opposing lane 202. For this reason, thereis a low possibility for traffic signals 210 to exist at positions thatare spaced apart from the traveling lane 200 and the opposing lane 202.Thus, according to the present embodiment, the lateral position of thesearch regions 232 a to 232 c is set to match with the trajectory of theroad lines 240 l, 240 r (see FIG. 2). In this case, the length in thelateral direction of the search regions 232 a to 232 c becomes smallerthan the initial settings. Along therewith, the range over which thesearch windows 230 a to 230 c are moved (or scanned) within the searchregions 232 a to 232 c becomes narrower.

(A2-2-3-2-2. Vehicle Velocity V)

If the vehicle velocity V is high, the necessity to issue a notificationof the illuminated state of a comparatively remote traffic signal 210becomes higher, whereas if the vehicle velocity V is low, the necessityto issue a notification of the illuminated state of a comparativelyremote traffic signal 210 becomes lower. Thus, according to the presentembodiment, the sizes of the search windows 230 a to 230 c and thesearch regions 232 a to 232 c are changed to match with the vehiclevelocity V. More specifically, if the vehicle velocity V is high, thefirst through third predetermined values L1 to L3 are made larger (e.g.,50 m, 100 m, 150 m) in relation to the distance L from the camera 20. Onthe other hand, if the vehicle velocity V is lower, the first throughthird predetermined values L1 to L3 are made smaller (e.g., 20 m, 40 m,60 m) in relation to the distance L from the camera 20. In accordancetherewith, the traffic signal 210 can be detected at a distance L thatcorresponds with the vehicle velocity V.

(A2-2-3-2-3. Yaw Rate Yr)

The trajectory of the road lines 240 l, 240 r is calculated based on thepresent peripheral image 100. For example, in the case that the absolutevalue of the left-oriented yaw rate Yr is large, the need to know theillumination state of the traffic signal 210 more to the left of thetrajectory of the road lines 240 l, 240 r becomes higher. Similarly, inthe case that the absolute value of the right-oriented yaw rate Yr islarge, the need to know the illumination state of the traffic signal 210more to the right of the trajectory of the road lines 240 l, 240 rbecomes higher. Thus, according to the present embodiment, the lateralposition of the search regions 232 a to 232 c is modified to match withthe yaw rate Yr. For example, the search regions 232 a to 232 c areshifted to the left side corresponding to an increase in the absolutevalue of the left-oriented yaw rate Yr.

(A2-2-3-2-4. Map Information Im)

Among the map information Im, concerning the distance information Ilmapto the traffic signal 210, a decision process is utilized to determinewhich of the search windows 230 a to 230 c and the search regions 232 ato 232 c will be used. For example, if the next traffic signal 210 is ata position that is farther away than the third predetermined value L3,the computation unit 52 uses only the search window 230 c and the searchregion 232 c, and the search windows 230 a, 230 b and the search regions232 a, 232 b are not used. Conversely, if the next traffic signal 210exists only in the vicinity of the first predetermined value L1, and thenext traffic signal 210 thereafter is at a position that is considerablyfarther than the third predetermined value L3, the computation unit 52uses only the search window 230 a and the search region 232 a, and thesearch windows 230 b, 230 c and the search regions 232 b, 232 c are notused.

Among the map information Im, concerning information (height informationIhmap) of the height H of the traffic signal 210, the range of thesearch regions 232 a to 232 c in the Y-axis direction (height direction)is limited in combination with the road line information Il and thedistance information Ilmap.

In the case that information (shape information) of the shape of thetraffic signal 210 is included in the map information Imp in combinationwith the road line information Io or the distance information Ilmap, therange of the search regions 232 a to 232 c is changed in the X-axisdirection (horizontal direction) and the Y-axis direction (heightdirection). For example, in comparison with a case in which the shape ofthe light emitting section 214 is horizontally long, for a case in whichthe shape of the light emitting section 214 is vertically long, theX-axis direction of the search regions 232 a to 232 c is made short,whereas the Y-axis direction thereof is made long. Accordingly, therange (and position) of the search regions 232 a to 232 c is setcorresponding to the shape of the light emitting section 214.

(A2-2-4. Detection of Traffic Signal 210 (Step S5 of FIG. 3))

The traffic signal detecting unit 66 moves (or scans) the search windows230 a to 230 c within the search regions 232 a to 232 c to therebydetect the traffic signal 210. For example, while the search window 230a is scanned from the left toward the right within the search region 232a, the traffic signal detecting unit 66 determines whether or notcharacteristics (e.g., shape, color, etc.) of the light emitting section214 or the lamps 220, 222, 224 of the traffic signal 210 exist withinthe search window 230 a. Next, while the search window 230 a is scannedfrom the left toward the right at a position lowered by a predetermineddistance, the computation unit 52 determines whether or not thecharacteristics (e.g., shape, color, etc.) of the traffic signal 210exist within the search window 230 a. By repeating the above steps, thesearch window 230 a is scanned over the entirety of the search region232 a. The same description applies to the search windows 230 b, 230 c.

During scanning of the search windows 230, the position of the searchwindows 230 at the present time is set so as to overlap with theprevious position of the search windows 230, at which the presence orabsence of the traffic signal 210 characteristics was determined. Statedotherwise, the offset amount of the previous search windows 230 to thepresent search windows 230 is shorter than the horizontal width (e.g.,half the horizontal width) of the search windows 230. Consequently, evenin the case that only a portion of the characteristics of the trafficsignal 210 appear within the previous search window 230 a and thetraffic signal 210 could not be detected, by all of the characteristicsof the traffic signal 210 appearing within the present search window 230a, the detection sensitivity for detecting the traffic signal 210 can beincreased. Further, overlapping of the previous position and the presentposition can be performed not only in the horizontal direction, but inthe vertical direction as well.

[A3. Advantages of the Present Embodiment]

As described above, according to the present embodiment, the searchregions 232 a to 232 c used during detection of the traffic signal 210become smaller as the distance L from the camera 20 (image capturingunit) is farther away (see FIG. 2). Therefore, the traffic signal 210can be detected with a small processing burden or computational loadcorresponding to the distance L from the camera 20. Alternatively, byshortening the processing cycle required to carry out searching of thesearch regions 232, the detection accuracy at which traffic signals 210are detected can be improved.

In the present embodiment, the traffic signal detecting unit 66 sets thesearch windows 230 a to 230 c for searching inside of the search regions232 a to 232 c, and scans the search windows 230 a to 230 c within thesearch regions 232 a to 232 c to thereby detect the traffic signal 210(FIG. 2, step S5 of FIG. 3). Further, the search windows 230 a to 230 cbecome smaller as the distance L from the camera 20 is farther away(FIG. 2). According to this feature, the traffic signal 210 can bedetected accurately by the search windows 230 a to 230 c correspondingto the distance L from the camera 20.

In the present embodiment, the surrounding environment recognitiondevice 14 is equipped with the road line detecting unit 60 (road linerecognition device) that recognizes the road lines 240 l, 240 r (FIG.1). The traffic signal detecting unit 66 changes the position of thesearch regions 232 a to 232 c corresponding to the position of the roadlines 240 l, 240 r (FIG. 2). According to this feature, by removing fromthe search regions 232 a to 232 c ranges in which the traffic signal 210cannot exist due to the relation thereof with the road lines 240 l, 240r, the computational load can be lightened, or accuracy can be enhancedaccompanying shortening of the search cycle.

In the present embodiment, the road line detecting unit 60 (road linerecognition device) acquires information of the distance Lsmap (distanceinformation Ilmap) to the traffic signal 210 from the map DB (thestorage device that is incorporated in the vehicle) of the mapinformation supply device 26, and sets the search regions 232 a to 232 cbased on the distance information Ilmap (step S4 of FIG. 3). Accordingto this feature, by specifying the distance L to the traffic signal 210using the distance information Ilmap, and setting the search regions 232a to 232 c based on the distance L, the accuracy in detecting thetraffic signal 210 can be enhanced, or a reduction in computational loadcan be realized.

In the present embodiment, the road line detecting unit 60 (road linerecognition device) acquires information of the height H (heightinformation) of the traffic signal 210 from the map DB (the storagedevice that is incorporated in the vehicle) of the map informationsupply device 26, and sets the search regions 232 a to 232 c based onthe height information of the traffic signal 210 (step S4 of FIG. 3).According to this feature, by specifying the height H of the trafficsignal 210 using the height information, and setting the search regions232 a to 232 c based on the height H, the accuracy in detecting thetraffic signal 210 can be enhanced, or a reduction in computational loadcan be realized.

B. Modifications

The present invention is not limited to the above embodiment, butvarious arrangements may be adopted based on the disclosed content ofthe present specification. For example, the following arrangements canbe adopted.

[B1. Object in which Recognition Device 14 is Incorporated]

In the present embodiment, the recognition device 14 is incorporated ina vehicle 10. However, the invention is not limited to this feature, andthe recognition device 14 may be incorporated in other objects. Forexample, the recognition device 14 can be used in mobile objects such asships and aircraft, etc. Further, the recognition device 14 is notlimited to being incorporated in mobile objects, and insofar as anapparatus or system is provided for detecting traffic signals 210, therecognition device 14 may be used in another apparatus or system.

[B2. Sensor Unit 12]

In the sensor unit 12 of the present embodiment, there are included thecamera 20, the vehicle velocity sensor 22, the yaw rate sensor 24, andthe map information supply device 26 (see FIG. 1). However, for example,from the standpoint of utilizing the search windows 230 a to 230 c andthe search regions 232 a to 232 c, the invention is not limited to thisfeature. For example, it is possible for one or more of the vehiclevelocity sensor 22, the yaw rate sensor 24, and the map informationsupply device 26 to be omitted. In the case that the map informationsupply device 26 is omitted (or stated otherwise, if the map informationIm is not used), traffic signals 210 are searched for using all of thesearch regions 232 for each of the distances L from the camera 20.

Alternatively, in addition to or in place of one or more of the vehiclevelocity sensor 22, the yaw rate sensor 24, and the map informationsupply device 26, other sensors can be used.

As one such other sensor, for example, an inclination sensor fordetecting an inclination A [deg] of the vehicle 10 (vehicle body) can beused. Corresponding to the inclination A, the computation unit 52 cancorrect the position in the Y direction (vertical direction) of thesearch windows 230 a to 230 c and the search regions 232 a to 232 c.

In the present embodiment, a situation has been assumed in which thecamera 20 is fixed to the vehicle 10. However, from the standpoint ofacquiring a peripheral image 100 in the direction of travel of thevehicle 10 (or mobile object), the invention is not necessarily limitedto this feature. For example. the camera 20 may be incorporated in amobile information terminal possessed by a passing pedestrian outside ofthe vehicle 10.

The camera 20 of the present embodiment is attached to the vehicle 10,and the specifications of the camera 20, e.g., magnification and viewangle, etc., are fixed. However, from the standpoint of acquiring aperipheral image 100 in the direction of travel of the vehicle 10 (ormobile object), the invention is not necessarily limited to thisfeature. For example, the specifications of the camera 20 may bevariable.

If the specifications of the camera 20 are variable, the currentspecifications of the camera 20 are notified to the computation unit 52of the recognition device 14 from a control unit (not shown) of thecamera 20. In addition, the computation unit 52 may set the searchwindows 230 a to 230 c and the search regions 232 a to 232 c to matchwith the current specifications of the camera 20. For example, if themagnification or view angle of the camera 20 is changed, even if thedistance L from the camera 20 is the same, the appearance of theperipheral image 100 changes. Therefore, the computation unit 52 setsthe search windows 230 a to 230 c and the search regions 232 a to 232 cto sizes that match with the change in appearance of the peripheralimage 100.

Alternatively, even if the camera 20 is attached to the vehicle 10 andthe specifications such as the magnification, view angle, etc., arefixed, a situation may be considered in which the specifications ofplural types of cameras 20 that are disposed in different vehicles 10are processed by computation units 52 having the same specification. Inthis case, specifications of the cameras 20 are stored beforehand instorage units (not shown) on the side of the cameras 20, and thecomputation units 52 may be used to read out the specifications of thecameras 20 from the storage units thereof.

With the above embodiment, the map DB 32 of the map information supplydevice 26 is disposed in the vehicle 10 (FIG. 1). However, from thestandpoint of acquiring map information Im, for example, the computationunit 52 may acquire map information Im from a non-illustrated externalserver (external device) or a roadside beacon.

[B3. Surrounding Environment Recognition Device 14]

The recognition device 14 of the above embodiment includes the road linedetecting unit 60 (FIG. 1). However, for example, insofar as the searchwindows 230 a to 230 c and the search regions 232 a to 232 c are capableof being utilized, the road line detecting unit 60 can be omitted.

[B4. Driving Assistance Unit 16]

The driving assistance unit 16 of the above embodiment includes thebrake device 70 and the warning device 72 (FIG. 1). However, forexample, from the standpoint of utilizing the search windows 230 a to230 c and the search regions 232 a to 232 c, the invention is notlimited to this feature. For example, it is possible for one or both ofthe brake device 70 and the warning device 72 to be omitted.

Alternatively, in addition to or in place of the brake device 70 and/orthe warning device 72, a different type of driving assistance device canbe provided. As examples of such different types of driving assistancedevices, there can be included a device (high efficiency driving supportdevice) for notifying the driver for the purpose of improving energyefficiency (fuel consumption, etc.). The high efficiency driving supportdevice can assist in high efficiency driving by prompting the driver tocontrol the vehicle velocity V so that the vehicle 10 is not required tostop at traffic signals 210.

The warning device 72 of the above embodiment serves to notify thedriver of the existence of a traffic signal 210 by displayinginformation on the display device 90 (see FIG. 1). However, for example,from the standpoint of notifying the driver of the existence of atraffic signal 210, the invention is not limited to this feature. Forexample, in addition to or in place of a display, the driver can benotified of the existence of the traffic signal 210 by way of a voiceoutput from a speaker.

[B5. Traffic Signal Detection Control]

In the above embodiment, the search windows 230 a to 230 c and thesearch regions 232 a to 232 c are set (step S3, S4 of FIG. 3) using theimage information Ii, the road line information Il, the vehicle velocityV. the yaw rate Yr, and the map information Im. However, for example,from the standpoint of utilizing the search windows 230 a to 230 c andthe search regions 232 a to 232 c, the invention is not limited to thisfeature. For example, it is possible for one or more of the road lineinformation Ii, the vehicle velocity V, the yaw rate Yr, and the mapinformation Im not to be used. In the case that only the imageinformation Ii is used without using the road line information Il, thecomputation unit 52 may use fixed positions for the search regions 232 ato 232 c.

What is claimed is:
 1. A surrounding environment recognition devicecomprising: an image capturing device that captures a peripheral image;and a traffic signal detecting controller, which sets a search regionwith respect to the peripheral image, and detects a traffic signalinside of the search region, wherein the traffic signal detectingcontroller sets a search window smaller than the search region andindicative of a range for searching inside of the search region, andscans the search window within the search region to detect the trafficsignal, the search region is controlled to be smaller as a distance fromthe image capturing device is farther away, and the search window iscontrolled to be smaller as the distance from the image capturing deviceis farther away.
 2. The surrounding environment recognition deviceaccording to claim 1, wherein: the surrounding environment recognitiondevice further comprises a road line recognition device that recognizesa road line; and the traffic signal detecting controller changes aposition of the search region corresponding to a position of the roadline.
 3. The surrounding environment recognition device according toclaim 2, wherein the road line recognition device acquires distanceinformation to the traffic signal from an external device or from astorage device incorporated in the vehicle, and sets the search regionbased on the distance information to the traffic signal.
 4. Thesurrounding environment recognition device according to claim 2, whereinthe road line recognition device acquires height information of thetraffic signal from an external device or from a storage deviceincorporated in the vehicle, and sets the search region based on theheight information of the traffic signal.
 5. The surrounding environmentrecognition device according to claim 1, wherein the traffic signaldetecting controller changes sizes of the search window and the searchregion depending on a velocity of a vehicle incorporating thesurrounding environment recognition device.
 6. The surroundingenvironment recognition device according to claim 1, wherein the trafficsignal detecting controller changes a lateral position of the searchregion depending on a yaw rate of a vehicle incorporating thesurrounding environment recognition device.
 7. The surroundingenvironment recognition device according to claim 1, wherein the trafficsignal detecting controller changes a range of the search regiondepending on shape information of the traffic signal included in mapinformation.
 8. The surrounding environment recognition device accordingto claim 1, wherein when scanning the search window, the traffic signaldetecting controller sets a position of the search window at the presenttime so as to be overlapped with a previous position of the searchwindow, at which presence or absence of characteristics of the trafficsignal was determined.
 9. The surrounding environment recognition deviceaccording to claim 1, wherein the traffic signal detecting controller isconnected to a driving assistance controller of a vehicle and supplies adetection result of the traffic signal to the driving assistancecontroller to activate a driving assistance control.